We are delighted to introduce you to Wes Carroll who has graciously created a few new puzzles to bend all those sharp brains out there! 
Wes is the head of Do The Math private tutoring services, Puzzle Master for the Ask A Scientist lecture series, and an internationally touring performer and teacher of music. With no further ado, the first puzzle!
Party For Polyglots
Difficulty: MEDIUM
Type: LOGIC
QUESTION:
Of the 100 people at a recent party, 90 spoke Spanish, 80 spoke Italian, and 75 spoke Mandarin. At least how many spoke all three languages?
Have you solved it yet? If you are working the problem, making hypotheses, testing your ideas, and coming up with a solution, you are using your frontal lobes. This is great exercise because the frontal lobes follow the “last hired, first fired” adage. They are they last areas of your brain to develop and the first to suffer the ravages of time and stress. So, keep exercising them!
ANSWER:
45
EXPLANATION:
10 could not speak Spanish, 20 could not speak Italian, and 25 could not speak Mandarin. So there could have been 10 people who spoke none of those languages.
However, that would maximize the number of people who could speak all three, and the problem asks at least how many speak all three. Therefore, we must assume that these 10, 20, and 25 people are all separate people. Having identified 55 each of whom is missing one language, the remaining 45 speak all three.
Next brain teaser in SharpBrains’ top 25 series:
- #15. Fun & Brainy Haikus. Yours?
